Different condenser microphones specify different amounts of required phantom power. As a rule these ratings can range from 48 volts all the way down to 9 volts. Fortunately, there is some flexibility in terms of matching phantom voltage to your mic. A rough rule of thumb would be "more is better."
For example, a 24-volt condenser mic will run perfectly on 48 volts. In fact, mics rated at as little as 9 volts can often operate on 48 volts, but you should check with the manufacturer first. Convers